Apparatus for screw cutting and feeds for machine tools



Gd. 9, 19.51 RU 2,570,720

APPARATUS FOR SCREW CUTTING AND FEEDS FOR MACHINE TOOLS 4 SheetsSheet 1Flled Sept. 21, 1946 I I I JF I K MARHN Hum R \NVE NToQ Oct. 9, 1951,RUMPF I 2,570,720

APPARATUS FOR SCREW CUTTING AND FEEDS FOR MACHINE TOOLS 4 Sheets-Sheet 2Filed Sept. 21, 1946 MARTiN HiNRI RuMPF IN v EN'TQ L Oct. 9, 1951 M. H.RUMPF 2,570,720

APPARATUS FOR SCREW CUTTING AND FEEDS FOR MACHINE TOOLS Filed Sept. 21,1946 4 Shee s-Sheet 3 v02 '02. 11-1: Em:

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APPARATUS FOR SCREW CUTTING AND FEEDS FOR MACHINE TOOLS Filed Sept. 21,1-946 4 Sheets-Sheet 4 F1! Ill].

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ATTORNEY Patented Oct. 9, 1951 APPARATUS FOR SCREW CUTTING AND FEEDS FORMACHINE TOOLS Martin Henri Rumpf, Uccle-Brussels, Belgium, assignor toLe Progres Industriel, Socit Anonyme, LothyBelgium, a Belgian companyApplication September 21, 1946, Serial No. 698,474 In Belgium September3, 1942 Section 1, Public, Law 690, August 8, 1946 Patent expiresSeptember 3, 1962 3 Claims. 7 1

My present invention relates to apparatus for screw cutting and feedsfor machine tools.

Machine tools (lathes, screw-cutting milling machines, grinding machinesfor screw threads) are provided at the option of the user with a metricor Whitworth (British thread) leading screw.

- To these leading-screws, correspond in the pitch box, reduction ratioswhich, conjointly with the ratios of the change wheels permit executingranges of pitch (ranges of metric, Whitworth, modulated, or diametralpitch). They may also provide'a range of carriage feeds.

In order to facilitate manipulation for obtaining a feed or a fixedpitch taken from one of these ranges, it will be evident that it isimportant to provide in the pitch box reduction ratios such as allow ofpreserving the same ratio of change wheels for difierent ranges, forexample (1) metric and Whitworth (2) modulated and diametral pitch.

The dismounting and. remounting of these wheels may thus be done awaywith the obtaining of a pitch may be effected by the simple manipulationof levers.

It isknown on the one hand that for the realisation of Whitworth pitchby means of a metrical feed screw or vice versa the number 127 being amultiple of 25.4 mm.=1 inch, a wheel of 127 teeth permits of givingthrough the ratios in which it comes into play a rigourously exactpitch, but for reasons of space taken up it is not generally possible toadapt in the pitch box ratios of reduction comprising this wheel of 127teeth. I

Absence of this wheel, therefore, imposes a search for ratios such thatthey may give, always without change of the change wheels, severaldifierent ranges of which the value of certain pitches, in default ofbeing rigourously exact, only depart from the theoretical pitch byinfinitesimal quantity, a quantity which is a function of the machiningtolerances admissible in screw cutting.

The pitches comprised in a range are obtained in general independentlyof the manipulation of other levers, by the displacement of a tiltingsliding gear called Norton system; this one sliding gear is displaced infront of a drum comprising a certain number of wheels. According towhether it is a question of a Whitworth, metric or modulated pitchsometimes the wheel controls the drum, sometimes the drum controls thewheel. That is an arrangement which pro- 2 vides a very simplecombination regarding the number of wheels, sliding gears, etc. However,the Norton sliding gear, besides the. lack of absolute rigidity of thetilting system, necessitates for the manipulation of the lever a largerecess in the front part of the housing; this recess, on the one hand,does not permit of lubrication by oil bath, the latter necessitating ahermetically sealed housing. On the other hand, the protection of themembers of the gear box cannot be ensured with certitude againsttheintroduction of filings, dust, etc. I

Whilst admitting that, by a system of protec{ tion, one may attain, tosome extent, a limita tion of the inconveniencesinherent in the recess,there remains nevertheless the inconvenience of the lack of rigidity ofthe tilting arrangement of which the removal can only be effected by atransformation of the whole ofthe device. With a view to remedying theseinconveniences there have already been constructed screw-cut; ting andfeeding apparatus, disposed in a housing without a recessin front, and.consequently entirely closed, allowing, by the displacement of a simplenon-tilting sliding gear, the obtaining of different ranges of pitch andof feed, without the changing of the change wheels and without a wheelof 127 teeth having to be interposed in the reduction ratio. The presentinvention relates to an apparatus of the kind characterized in that itcomprises sliding gear-wheels which may be displaced by sliding on thesame spindle and of which each meshes with at least two fixed wheelsdisposed about a single axis, having different numbers of teeth and ofwhich the teeth as a development of a circle are corrected positively ornegatively, so that the gearing is effected normally with thecorresponding tilting gear, although the number of teeth of the fixedwheels may be different and the distance between centers may beconstant. The apparatus may comprise a plurality of fixed wheelspindles, each of the sliding wheels being able to simultaneously engagewith fixed wheels belonging to several spindles, each of the lattertransmitting alternatively the movement towards the delivery spindle ofthe apparatus. The arrangement brings about for a number of equalspeeds, an appreciable reduction in the length of the spindles relativeto present arrangement in which each sliding wheel only gears with asingle fixed wheel and in which the fixed Wheels are all aligned on oneand the same spindle. Y r r Y Thes annexed drawings are intended to showhow the invention may be practically embodied and also to illustrate itsadvantages.

Fig. 1 shows a sliding wheel arrangement of the type. according to thepresent invention.

Fig. 2 shows a sliding wheel arrangement of known type.

Fig. 3 is a sectional view of a box constructed in accordance with theinvention.

Fig. 4 schematically shows the transmission of the movement across thebox.

Figs. 5, 6, '7 and 8 illustrate how a gear box constructed in accordancewith the principl s of the invention may be fixed on diiierent plateshaving different dimensions.

Fig. 9 is an illustrative example of a screw cutting apparatus inaccordance with my invention.

Fig. 10 shows my invention as applied to a Fellow cutting tool.

Fig. 11 illustrates the Norton system, and

Figs. 12, 1'3 and 14 illustrate gear wheels schematically, the pitchcircles being indicated on these figures.

As is shown in Fig. 1, the arrangement according to the presentinvention, employmentis made of spindles 66 on which are keyed, onspindle 6, wheels a1, a2, a3}31, [32, B3 and on spindle B the wheels v1,72, 'y351, 62, 63. On a spindle 1- parallel to the spindles 6-6 aremounted sliding wheels I and 2 which may slide on this spindle T andturn therewith.

The wheels mounted on the spindles B and 6 comprise four groups eachwheel having a different number of teeth and their teeth are such thatthe gearing is normally eifected with the corresponding sliding wheell-2, although the diameter ofthe wheel-in each group is approximatelythe same and the distance between the centres is constant.

A- sleeve 8 connected with the delivery spindle (not shown) carriesa-third sliding wheel-3--which may gear either with a wheel 9 fixedonspindle B or (after sliding into position 3 with a-wheel l-ll fixed onthe spindle 6;

Thus there are obtained, by means of this arrangement, 12 differentratios, with 1-4 wheel's and-'3 single-wheeled sliding gears, of whichtwo, sliding gears and-2--give velocities properly socalled and a third(sliding-gear 2) transmitstcwards the delivery spindles the velocitiesobtained on one or the other of the spindles 6-45 carrying the fixedwheels.

In the known system, these- 12-ratios --can-only be obtained by meansof- 12 wheelsandotsix sliding-gears with two wheels-each, distributedon. the same spindle, as illustrated in. Fig. .2.

The gist of the invention lies in the meshing of a. slidable wheelalternatively with several. rigidly mounted wheels. set on the same.spindle, that have difierent numbers of teeth, but. all having thesamediameter.

Thedistance between the spindles, is thereforeconstant and the spindleof the sliding .gear maybe fixed like thatofthegear train.

Letus. takev a Fellow cutting tool 2;] (Fi ..10). This tool, may cutdifierent. numbers of. teeth in round blanks 22 of the same. diameter,for instance: 16, 17, 18, 19, 20 andl2l. teeth or 22,to 28 teethetc.

Imagine this cutter replacedby a sliding. gear wheel of. same pitch andof same diameter. It will be. easy to understand the possibilities forunyarying distances between the, spindles, of making this wheel meshwith other rigidly mounted wheelshavingv ryina umberszo te t Thisprinciple is capable of different applica tions. For instance, the sameslidable wheel may mesh with wheels belonging to 2. (or more) sets ofrigidly mountedwheels.

Let us take:

1. A series of gear wheels of the same pitch with different numbers ofteeth and cut according to standard methods by the same Fellow cutter.This is the practice of the Norton system (Fig. 11).

The base diameter will vary in proportion to the number of teethaccording to the relation:

Db=M.N cos where M=pitch of the cutting tool N=numberof teeth a=pressureangle of the cutting tool.

Remembering that the pitch circle is that from which. the involute ofthe circle originat that forms the cutting, edgeof the. t oth (Fig. 12)the pitch circle governs the basic characteristics ofa gearing withteeth definedbyi theinvolute of a circle.

2. A series of wheels out under the same condi, tions having the samenumbers of teeth as. the. precedin ones and all; with thesameoutsidediameter, which is comprised within the. range resp clinev t0. h Whe l.consideredinthe case of the Norton system, (Fig. 3.0.)

he p tc i cl r main unerposed the om y, B t heu d b no cedthat the t n fhe s e nes; under han es. in relat to th tandard ofile. in pr port o-Jae; the number of teeth oi the wheels ,(Figs 13 and 14). These changesexpress a, variationpi the pitch andof the pressure angle. Alltheuwheels, remain linked together by the, invariabilityof; th base.pitch, h i itch nd th i an wmnhr with the relation:

In practice, it is adyisabl'eto takeinto-consideration the figure forlag, thickness of teeth at. their apex andat theira-base, soas to. keepthese elements within acceptable ranges.

By. taking into account these-.elements...it is possible to. ensurethesame uninterrupted .meshe ing as in the. caseiof. standard. gearings andeven to improve, forcertain ratios, the. specificsliding capacity.

It will be understood that the...more.,the-num. ber of velocities orspeed. changesrequired. in:

, creases, the more possibilities there are by means:

of the arrangement. ac.c,ording,..t0 the-princi shown in Fi 1. of.comparatively.reducin the. number of. sliding gears and he, length, oi.the wholeerra emen h s d m ution ii-len th itseljallows for an equalreduction in dian eter, of the. spindles, of the weight of the latterand; inconsequence, of reduction of :the, forcesof; in ertia,"independently of the economy efiect'ed material. The sliding gears I, 2each comprise a single wheel and are actuated by a single leveracting ona cam, articulated levers or other means.

The advantages of this arrangement are o1? two kinds: i

(a) The employment of single lever considerably simplifies themanipulation and reduces to a. minimum thev risks of errorsstartingufrom the necessary ma p atieni rthe ob ainin of; a iventhre oroeeirened; :1, I (b) Th G m .erartic la e. evers m de. the

simultaneous displacement of the sliding gears; j in fact, in the caseofa plurality of leversyit would be necessary to provide asecurityarrangement relatively complicated (grooved sectors, lockingplungers, etc.) On the other hand, starting from the manipulation, itwill be necessary, before actuating the lever controlling the slidinggear corresponding to the desired pitch or to the desired feed, to bringback to the dead or disengaged position the sliding gear in use.

Fig. 3 shows a developed view of the general elements'of a changespeed-gear box which is the, object of the'present invention as appliedto alathe.

' In this gear-box, the spindle I 8 drives a spindle I by means ofchange wheels schematically illustrated at l9. On this spindle I theremay slide a sliding gear B.l simultaneously with a sliding gear 3.3keyed to spindle e r The sliding gear B! may gear With-a wheel (1 keyedon the spindle 2 or with a wheel e keyed to the spindle 3. The slidingear 13.3 may engage With a wheel 1 also keyed on the spindle 3 or withthe wheel g keyed on the spindle 2.

The spindle 2 carries a 'sliding'gear'Bl and a drum A freely turning onthis spindle. The sliding gear 32 may drive either the drum A by meansof direct engagement or by an intermediate wheel h turning freely on 3and wheel :1, it may drive a drum C turning freely on spindle 5.

The sliding wheel a may engage with wheels k, Z, m, n.

The sliding wheel 11 may engage with the wheels 19, q, r, s.

The sliding wheel may gear with the wheels t, u, v, w.

The sliding of these wheels a, b, c, is effected by a single leveracting through the intermediate agency of a cam.

The simultaneous displacement of the sliding gears BI and 13.3 renderseither spindle 2 of the driving spindle of the spindle 3 (for obtaininga metrical pitch) or the spindle 3 the driving spindle of the spindle 2(for obtaining Whitworth pitch), the drive coming initially from spindleI. The diagram 4 schematically illustrates the above-mentionedarrangement.

In the position illustrated, in Fig. 3 for the sliding gears B.IB.3, andthe sliding gear B2, the sliding gear 3.! actuates the wheel d whichdrives the spindle 2, and the transmission is effected through 3.2, thewheels h, 7, m, the wheel a, the spindle 3, the wheel 1, the slidinggear B.3 and the spindle 4.

When the sliding gears BI and 3.3 are displaced to their alternativepositions, transmission is effected by the wheel 6, the spindle 3, theWheel a, the wheel m, the wheels 7', h, B2, the wheel g, the slidinggear 3.3 and the spindle 4.

The different velocities are transmitted by the spindle a which, throughthe intermediate agency of the different fixed ratios, for example 1/1,1/2, 1/4 and 1/8, controls the head screw and the carriage feed shaft.

With the object of utilizing one and the same gear box for various kindsof machines, the housing ll (Fig. 5) in which are lodged the variousmembers illustrated in Fig. 3, is formed so as to allow of its beingfixed to different plates I2 of which the dimensions vary according tothe structure in which they are fixed.

In the case of a lathe, the output spindle l3 (Fig. 6) of the changerspeed gear ll controls the lead screw [4 and the feed shaft [5 throughthe intermediate" agency of the "gears" IG- F6 -The bearings of the leadscrew l4 and .the bearings of the feed shaft l5 are disposed inanindependent support I1 (Fig. 8) fixed to the structure. a

=It is thus possible to ensure the action of the zation of the samechange-speed gear box for.

various typesof machines for which:

(a) The structures 'may be different; (b) The positions of the leadscrew and of the feed shaft maybe any suitable ones relative to thedelivery spindle ofthebox. 1

. The principle of gearing sliding gear with several fixed wheels ofthesame diameter; but with small differences in their numbers of teeth maybe applied not only in the case of a wheel with straight teeth .butalsowith wheels with helicoidal teeth. .1 1 Fig, 9 -illustrates by way ofexample a screw cutting apparatus comprising this modification.

In this apparatus, employment is made of spindles 66 on which are keyed,on spindle 6, the wheels with helicoidal teeth al, a2, a3 a6 and onspindle 6 the wheels ,81, 82 186 also with helicoidal teeth. On thespindle 1 parallel to spindles 6-6 and provided with a helicoidal keygroove, is mounted a sliding gear I which may slide on this spindle 1and turn therewith.

As for Figs. 1-4, 3 designates a sliding gear which can engage eitherwith a fixed wheel 9 on the spindle 6 or (after sliding into theposition 3 with a fixed wheel Ill on the spindle 6. This: sliding gear 3is carried by a sleeve 8 in relationship with the output spindle (notshown).

Thus the number of wheels of the same external diameter but comprisingdifferent numbers of teeth with which the same sliding gear may engagemay be increased by this arrangement.

Having now particularly described and ascertained the nature of myinvention, and in what manner the same is to be performed, I claim:

1. In a screw-cutting and feed-movement gear for machine-tools, incombination with a first spindle, a slidable gear mounted on said firstspindle and adapted to turn therewith, a plurality of other spindlesparallel to the first spindle, wheels rigidly mounted and set on saidother spindles, all the fixed wheels belonging to the same spindlehaving different numbers of teeth, all having the same outside diameterand the teeth of which are defined by the involute of a circle, thesliding gear wheel being adapted to engage simultaneously and correctlywith the fixedwheels belonging to different spindles, a driven spindleand means whereby each of the latter transmits alternatively themovement towards the driven spindle.

2. In a screw-cutting and feed-movement gear for machine-tools, incombination with a first spindle, slidable gears mounted on said firstspindle and adapted to turn therewith, a plurality of other spindlesparallel to the first spindle, groups of wheels rigidly mounted and seton said other spindles, all the fixed wheels of one group havingdifferent numbers of teeth, all having the same outside diameter and theteeth of which as an involute of a circle are corrected positively ornegatively so that the engagement corresponding to one group, and eachsliding; wheel; bein adapted;- to en a e simmte egu wandveorreetlyt'with the; fixed: wheels Q groups; belon in tn. difierent;spindlesi a driven. p ndle, and means whereby each of the latteralternatiyelyi the; moi/lenient towards the; driven spindles V Gentnormally; ta mi place ililil' lil:x thG: sliding;- M 131? first spindle;alslidahle; ear mounted; am said first; spindle.- and= adapted; to. vtumthenewitzhl a. plurali y of. other spindles: parallela to the. first.spindle, wheels;nig-id.1y mounted. and: set; on said. h r pindles allthfixed wheels belon in to the; samespinclle haying different numbers ofteeth, all haying the-same; out-side diameter and, the teeth of whichas; an; imiolilba off; a circ1ea, 1:e correctedx positively r.negatively so. that. the en agement. can: n rmalls; take place: with.the. slidin Wheel, the; sliding ear wheel: being. adapted to engagesimultaneously and correctly with; thefixml Wheelsbelonging 130;different spindles, a driven spindle and means whereby each of: thelatter transmits. alternatively the mwem m: q ezd th m npin le lth u h?REFEBENGES. CITED- Tihe follewing-lzefenenms are ofrecord; in the; fileof this patent: ear for machm -tools, .lll combination w th a. 1.0

UNITE-D" STATES PATENTS Mumber Name Date 7 A 106,136 LeBlond. Aug. 5,1902}; 772,246 Miller Oct; 11, L994},

13520545 Dec. 23, 192

$4,039 siege 1 2 2,205,473 Fishburn June 25 19kt) 2 4 15;,125- DavenportFeb. 4419A? FOREIGN PATENTS Number Country Date 420,562 Germany. Oct. 21925v 735,414 France Nov. 8, L932

